Abstract

Rationale

Guanfacine is an α2-adrenergic receptor agonist that has been shown to have beneficial effects on working memory and attentional functions in monkeys and in patients with attention deficit hyperactivity disorder.

Objectives

The aim of this study was to further investigate the cognitive-enhancing properties of guanfacine using an established battery of tasks measuring executive and memory functions.

Methods

Sixty healthy male volunteers were randomised into three groups. Cognitive testing was performed from +2 to +4 h after double-blind administration of a single oral dose of 1 or 2 mg of guanfacine or placebo.

Results

Systolic blood pressure was significantly reduced by both doses of guanfacine at the end of the testing session. There were no statistically significant effects on any of the cognitive measures. Two trend effects were observed with poorer performance on digit span backward and slower ‘Go’ reaction times after guanfacine.

Conclusion

This study found no improvement of prefrontal memory or executive functions after guanfacine. Negative effects on blood pressure and trend effects on digit span backward and go reaction time indicate a mild sedative effect of guanfacine at these doses, possibly via mechanisms of autoreceptor down-regulation.

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